Atraumatic coupling and catheter employing the same

ABSTRACT

A catheter includes a proximal shaft and a distal shaft having differing diameters; often, the distal shaft will have a smaller diameter than the proximal shaft. A coupling joins the distal shaft to the proximal shaft. For example, a proximal portion of the distal shaft can be inserted into the coupling through its distal end, while the proximal portion of the coupling can be inserted into the proximal shaft through its distal end. To provide an atraumatic transition from the distal shaft to the proximal shaft, coupling can taper towards its distal end, for example by using a dome- or frustoconical-shape for the distal portion of the coupling. The exterior of the coupling can be ribbed to facilitate bonding to the proximal shaft. The distal shaft can be formed into at least a partial loop having a fixed or variable radius of curvature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.62/280,159, filed 19 Jan. 2016, which is hereby incorporated byreference as though fully set forth herein.

BACKGROUND

The instant disclosure relates to catheters for use in medicalprocedures, such as electrophysiology studies. In particular, theinstant disclosure relates to an atraumatic coupling that can be used tojoin two shafts of unequal size.

Catheters are used for an ever-growing number of procedures, such asdiagnostic, therapeutic, and ablative procedures, to name just a fewexamples. Typically, the catheter is manipulated through the patient'svasculature and to the intended site, for example, a site within thepatient's heart.

A typical electrophysiology catheter includes an elongate shaft and oneor more electrodes on the distal end of the shaft. The electrodes may beused for ablation, diagnosis, or the like. Oftentimes, these electrodesare ring electrodes that extend about the entire circumference of thecatheter shaft.

One specific use of an electrophysiology catheter is to map the atrialregions of the heart, and in particular the pulmonary veins, which areoften origination points or foci of atrial fibrillation. Suchelectrophysiology mapping catheters typically have at least a partialloop shape at their distal end, oriented in a plane generally orthogonalto the longitudinal axis of the catheter shaft, which allows the loop tosurround the pulmonary vein ostia.

Further, the more proximal and elongate region of the shaft often has alarger diameter than the more distal region (e.g., the portion formedinto at least a partial loop). Thus, there is a need to transition fromthe larger diameter proximal shaft to the smaller diameter distal shaft.

BRIEF SUMMARY

Disclosed herein is a catheter including: a proximal shaft having afirst diameter; a distal shaft having a second diameter different fromthe first diameter; and a coupling joining the proximal shaft to thedistal shaft, the coupling having a hollow interior and including adistal portion and a proximal portion, wherein a proximal portion of thedistal shaft is inserted into the hollow interior of the couplingthrough a distal end of the coupling and the proximal portion of thecoupling is inserted into the proximal shaft through a distal end of theproximal shaft.

In embodiments, the catheter also includes a sensor having a hollow coredisposed within a distal portion of the proximal shaft, wherein theproximal portion of the coupling is inserted into the hollow core of thesensor and the distal portion of the proximal shaft. The proximalportion of the coupling can include a first sub-portion having an outerdiameter small enough to allow insertion into the hollow core of thesensor; and a second sub-portion having an outer diameter small enoughfor insertion into the distal portion of the proximal shaft, but toolarge for insertion into the hollow core of the sensor, wherein thesecond sub-portion is positioned distally of the first sub-portion.

According to aspects of the disclosure, an outer diameter of thecoupling is smaller at the distal end of the coupling than at a pointadjacent the distal end of the proximal shaft. For example, the distalportion of the coupling comprises can include dome shaped portion and/ora frustoconical portion.

According to other aspects of the disclosure, a maximum outer diameterof the proximal portion of the coupling is less than a maximum outerdiameter of the distal portion of the coupling.

The hollow interior of the coupling can include an abutment surface forthe proximal portion of the distal shaft, which stops the advancement ofthe distal shaft into the coupling at a desired depth. It is alsocontemplated that the coupling can cause the distal shaft to bepositioned coaxially within the proximal shaft.

In embodiments, an exterior surface of the coupling includes a pluralityof ribs. The coupling can also be made out of a clear polymericmaterial, for example to facilitate visualization of the distal shaftwithin the coupling.

The distal shaft can be formed into at least a partial loop. The radiusof curvature of the loop can be fixed or variable.

Also disclosed herein is a method of manufacturing a catheter,including: providing a proximal shaft having a first diameter, a distalshaft having a second diameter different from the first diameter, and acoupling having a hollow interior; inserting a proximal portion of thedistal shaft into the hollow interior of the coupling through a distalend of the coupling; inserting a proximal portion of the coupling intothe proximal shaft through a distal end of the proximal shaft; securingthe distal shaft to the coupling; and securing the proximal shaft to thecoupling.

The hollow interior of the coupling can include an inner abutmentsurface, such that inserting a proximal portion of the distal shaft intothe hollow interior of the coupling through a distal end of the couplingcan include advancing the proximal portion of the distal shaft into thehollow interior of the coupling until a proximal end of the distal shaftabuts the inner abutment surface. Similarly, an exterior surface of thecoupling can include an outer abutment surface, such that inserting aproximal portion of the coupling into the proximal shaft through adistal end of the proximal shaft can include advancing the proximalportion of the coupling into the proximal shaft until the distal end ofthe proximal shaft abuts the outer abutment surface.

According to aspects of the disclosure, the manufacturing method alsoincludes: providing a sensor having a hollow core; inserting theproximal portion of the coupling into the hollow core of the sensor; andinserting the proximal portion of the coupling and the sensor into theproximal shaft through the distal end of the proximal shaft.

The distal shaft, coupling, and proximal shaft can be secured to eachother, for example, using an ultraviolet curing adhesive.

In another aspect, the present disclosure provides an atraumaticcoupling for securing a first shaft segment to a second shaft segmenthaving a different outer diameter from the first shaft segment. Thecoupling includes: a proximal portion having an exterior surface, theexterior surface of the proximal portion including a plurality of ribs,and wherein an outer diameter of the proximal portion is not greaterthan an inner diameter of the first shaft segment; and a distal portion,the distal portion having an exterior surface that tapers from a pointat which the proximal portion meets the distal portion to a distal tipof the distal portion, and wherein an outer diameter of the distalportion at the point at which the proximal portion meets the distalportion is about equal to an outer diameter of the first shaft segment,wherein at least the distal portion defines an interior cavity of thecoupling, and wherein a diameter of the interior cavity of the couplingis not smaller than an outer diameter of the second shaft segment. It iscontemplated that the coupling can include a clear polymeric material.

The foregoing and other aspects, features, details, utilities, andadvantages of the present invention will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate exemplary electrophysiology catheters.

FIG. 3 is a close up of a portion of an electrophysiology catheteraccording to some embodiments of the instant disclosure.

FIG. 4 depicts the assembly of a distal shaft, a proximal shaft, acoupling, and a sensor according to aspects of the disclosure.

FIG. 5A is a perspective view of an embodiment of a coupling asdisclosed herein.

FIG. 5B is a cross-sectional view of the coupling of FIG. 5A.

FIG. 6 is a simplified cross-sectional assembly drawing of a distalshaft, a proximal shaft, a coupling, and a sensor as disclosed herein.

FIG. 7 is a cross-sectional view of another embodiment of a coupling asdisclosed herein.

FIG. 8 is a perspective view of still another embodiment of a couplingas disclosed herein.

DETAILED DESCRIPTION

For the sake of illustration, certain embodiments of the disclosure willbe explained herein with reference to an electrophysiology catheterutilized in cardiac electrophysiology studies. It should be understood,however, that the present teachings may be applied to good advantage inother contexts as well.

Referring now to the figures, FIGS. 1 and 2 depict two embodiments of anelectrophysiology (“EP”) catheter 10 according to aspects of the presentdisclosure. EP catheter 10 includes catheter body 12, which in turnincludes a proximal shaft 14, a distal shaft 16, and a coupling 18 thatjoins proximal shaft 14 and distal shaft 16 as discussed herein. In someembodiments, catheter body 12 is tubular (e.g., it defines at least onelumen therethrough). It should also be understood that the relativelengths of proximal shaft 14, distal shaft 16, and coupling 18 asdepicted in FIGS. 1 and 2 are merely illustrative and may vary withoutdeparting from the spirit and scope of the instant disclosure. Ofcourse, the overall length of catheter body 12 should be long enough toreach the intended destination within the patient's body.

Catheter body 12 will typically be made of a biocompatible polymericmaterial, such as polytetrafluoroethylene (PTFE) tubing (e.g., TEFLON®brand tubing). Of course, other polymeric materials, such as fluorinatedethylene-propylene copolymer (FEP), perfluoroalkoxyethylene (PFA),poly(vinylidene fluoride), poly(ethylene-co-tetrafluoroethylene), andother fluoropolymers, may be utilized. Additional suitable materials forcatheter body 12 include, without limitation, polyamide-basedthermoplastic elastomers (namely poly(ether-block-amide), such asPEBAX®), polyester-based thermoplastic elastomers (e.g., HYTREL®),thermoplastic polyurethanes (e.g., PELLETHANE®, ESTANE®), ionicthermoplastic elastomers, functionalized thermoplastic olefins, and anycombinations thereof. In general, suitable materials for catheter body12 may also be selected from various thermoplastics, including, withoutlimitation, polyamides, polyurethanes, polyesters, functionalizedpolyolefins, polycarbonate, polysulfones, polyimides, polyketones,liquid crystal polymers and any combination thereof. It is alsocontemplated that the durometer of catheter body 12 may vary along itslength. In general, the basic construction of catheter body 12 will befamiliar to those of ordinary skill in the art, and thus will not bediscussed in further detail herein except to the extent necessary tounderstand the instant disclosure.

As seen in FIG. 3, distal shaft 16 can be predisposed into at least apartial loop. This loop shape allows distal shaft 16 to conform to theshape, for example, of a pulmonary vein ostium. The partial loop maytake a number of configurations, depending on the intended or desireduse of EP catheter 10, consistent with the present teachings. Therefore,it should be understood that the loop configuration depicted in FIG. 3is merely illustrative.

FIG. 3 also illustrates that distal region 16 can include a plurality ofelectrodes 20 disposed thereon. Electrodes 20 may be ring electrodes orany other electrodes suitable for a particular application of EPcatheter 10. For example, where EP catheter 10 is intended for use in acontactless electrophysiology study, electrodes 20 may be configured asdescribed in U.S. application Ser. No. 12/496,855, filed 2 Jul. 2009,which is hereby incorporated by reference as though fully set forthherein. Of course, in addition to serving sensing purposes (e.g.,cardiac mapping and/or diagnosis), electrodes 20 may be employed fortherapeutic purposes (e.g., cardiac ablation and/or pacing).

FIG. 3 further illustrates that the outer diameter of proximal shaft 14differs from the outer diameter of distal shaft 16. For example, theouter diameter of proximal shaft 14 can be 8 French (0.104 inches),while the outer diameter of distal shaft 16 can be 4 French (0.052inches). Thus, coupling 18 secures proximal shaft 14 to distal shaft 16while providing an atraumatic transition from the outer diameter of oneto the outer diameter of the other as discussed in further detail below.This is also illustrated to good advantage in FIG. 4.

Referring again to FIGS. 1 and 2, a handle 22 is coupled to catheterbody 12. Handle 22 includes suitable actuators (e.g., actuator 24 a inFIG. 1; actuator 24 b in FIG. 2) to control the deflection of catheterbody 12, for example as described in U.S. Pat. No. 8,369,923, which ishereby incorporated by reference as though fully set forth herein.Various handles and their associated actuators for use in connectionwith electrophysiology catheters are known, and thus handle 22 will notbe described in further detail herein.

Although in some embodiments, the radius of curvature of the loop ofdistal shaft 16 may be fixed, it is also contemplated that it may beadjustable, for example to conform to the varying sizes of pulmonaryvein ostia of patients of different ages. This additional control may beprovided, for example, via the use of an activation wire that is adaptedto alter the radius of curvature of the loop of distal shaft 16. Onesuitable material for such an activation wire is stainless steel, thoughother materials can be employed without departing from the spirit andscope of the instant disclosure.

In some embodiments, one end (e.g., the distal end) of the activationwire may be coupled to the tip of catheter body 12 (e.g., coupled to adistal-most tip electrode of electrodes 20), while the other end (e.g.,the proximal end) of the activation wire may be coupled to an actuator(e.g., a thumb slider) on handle 22. Thus, for example, sliding thethumb slider proximally can place the activation wire in tension,thereby altering the radius of curvature of the loop of distal shaft 16.

Another exemplary mechanism for varying the radius of curvature of theloop of distal shaft 16 is described in U.S. Pat. No. 7,606,609, whichis hereby incorporated by reference as though fully set forth herein.

A first embodiment of coupling 18 is depicted in perspective view inFIG. 5A and in cross-section in FIG. 5B. As shown in FIGS. 5A and 5B,coupling 18 includes a hollow interior 28. As used herein, the term“hollow interior” means that there is at least one cavity within theinterior; the term “hollow core” is used synonymously in thisdisclosure. Although this cavity is depicted in FIGS. 5A and 5B asextending throughout the entire length of coupling 18 with asubstantially constant diameter, the term “hollow” is not intended to beso limited. Thus, the diameter of the cavity can vary along the lengthof coupling 18 and still be considered “hollow” within the meaning ofthe instant disclosure.

Coupling 18 includes a distal portion 30 and a proximal portion 32. Asshown in the simplified assembly drawing of FIG. 6, distal portion 30 ofcoupling 18 receives distal shaft 16 (e.g., the proximal portion 34 ofdistal shaft 16 is inserted into hollow interior 28 of coupling 18through the distal end 36 of coupling 18). Similarly, proximal portion32 of coupling 18 is received into proximal shaft 14 (e.g., proximalportion 32 of coupling 18 is inserted into proximal shaft 14 through thedistal end 38 of proximal shaft 14).

FIGS. 5A, 5B, and 6 also illustrate that the outer diameter of coupling18 changes along its length. In particular, the outer diameter ofcoupling 18 is narrower at its distal end 36 than it is at a pointadjacent distal end 38 of proximal shaft 14. That is, distal portion 30of coupling 18 tapers towards its distal end 36 and can, in embodiments,include a dome-shape as shown in FIGS. 5A, 5B, and 6. In otherembodiments, such as shown in FIG. 7, distal portion 30 of coupling 18can include a frustoconical shape.

According to aspects of the disclosure, the maximum outer diameter ofproximal portion 32 of coupling 18 is less than the maximum outerdiameter of distal portion 30 of coupling 18. It is further contemplatedthat the outer diameter of the distal portion 30 of coupling 18 wheredistal portion 30 meets proximal portion 32 (e.g., a point adjacentdistal end 38 of proximal shaft 14 when catheter 10 is assembled) isabout equal to the outer diameter of proximal shaft 14 in order tofacilitate a smooth transition to proximal shaft 14. Thus, for example,if proximal shaft 14 has an 8 French outer diameter, then the outerdiameter of coupling 18 where distal portion 30 thereof transitions toproximal portion thereof can also be about 8 French. There can, however,be about an 8% difference in these outer diameters without adverselyaffecting the smooth and atraumatic transition provided by thecombination of the tapering shape of distal portion 30 and the relativediameters of distal portion 30, proximal portion 32, and proximal shaft14 (e.g., as shown in FIG. 4).

As shown in FIGS. 6 and 7, proximal portion 32 of coupling 18 caninclude an abutment surface 40. Abutment surface 40 stops theadvancement of distal shaft 16 into hollow interior 28 of coupling 18.That is, distal shaft 16 is advanced into hollow interior 28 of coupling18 until the proximal portion 34 of distal shaft 16 abuts the abutmentsurface 40 (see FIG. 6).

The exterior surface of proximal portion 32 of coupling 18 can alsoinclude one or more ribs 42. Ribs 42 can increase the bondabilitybetween coupling 18 and proximal shaft 14, for example by creating amechanical lock with the adhesive used to attach coupling 18 to proximalshaft 14.

FIG. 8 depicts an additional embodiment of coupling 18 that isconfigured to facilitate the positioning of an additional sensor 44(shown in FIGS. 4 and 6) along catheter body 12. In the embodiment ofcoupling 18 depicted in FIG. 8, proximal portion 32 of coupling 18includes a first sub-portion 46 and a second sub-portion 48. Firstsub-portion 46 has an outer diameter small enough for insertion into ahollow core of sensor 44 such that, for example, sensor 44 is advanceduntil it abuts surface 50 at the transition between first and secondsub-portions 46, 48 (which can be the opposite side of abutment surface40 against which distal shaft 16 abuts).

Second sub-portion 48, which is distal of first sub-portion 46, has anouter diameter small enough for insertion into proximal shaft 14, buttoo large for insertion into the hollow core of sensor 44. Secondsub-portion 48 (and thus proximal portion 32) ends at surface 52, whichrestricts the advancement of coupling 18 into proximal shaft 14 duringassembly.

Alternatively, coupling 18 can also serve as a datum for positioning oneor more sensors 44 without having coupling 18 inserted therein.

In embodiments, coupling 18 can be made of a clear polymeric material.The use of a clear polymeric material enables the use of an ultravioletcuring adhesive to join coupling 18 to distal shaft 16. It alsofacilitates visual confirmation that distal shaft 16 is properlypositioned within coupling 18. Of course, in other embodiments, coupling18 can be translucent or opaque.

Assembly of catheter body 12 can be understood with reference to FIG. 6.Distal shaft 16 is inserted into hollow interior 28 of coupling 18through the distal end 36 of coupling 18 until proximal portion 34 ofdistal shaft 16 reaches the abutment surface 40 within proximal portion32 of coupling 18.

Optionally, a hollow core sensor 44 can be fit over first sub-portion 46of proximal portion 32 of coupling 18, for example until sensor 44 abutssurface 50. Proximal portion 32 of coupling 18 (and sensor 44, ifpresent) can then be inserted into proximal shaft 14 through distal end38 of proximal shaft 14, for example until distal end 38 of proximalshaft 14 abuts surface 52.

Advantageously, coupling 18 facilitates coaxial alignment betweenproximal shaft 14, sensor 44 (if present), and distal shaft 16. Once thedesired alignment is achieved, the various components can be secured toone another, for example via the use of an ultraviolet curing adhesive.

Although several embodiments of this invention have been described abovewith a certain degree of particularity, those skilled in the art couldmake numerous alterations to the disclosed embodiments without departingfrom the spirit or scope of this invention.

For example, although certain exemplary embodiments have been describedabove with reference to a unitary coupling 18, it is contemplated thatcoupling 18 can also include multiple constituent parts that are matedtogether during assembly of catheter 10.

All directional references (e.g., upper, lower, upward, downward, left,right, leftward, rightward, top, bottom, above, below, vertical,horizontal, clockwise, and counterclockwise) are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations, particularly as to theposition, orientation, or use of the invention. Joinder references(e.g., attached, coupled, connected, and the like) are to be construedbroadly and may include intermediate members between a connection ofelements and relative movement between elements. As such, joinderreferences do not necessarily infer that two elements are directlyconnected and in fixed relation to each other.

It is intended that all matter contained in the above description orshown in the accompanying drawings shall be interpreted as illustrativeonly and not limiting. Changes in detail or structure may be madewithout departing from the spirit of the invention as defined in theappended claims.

What is claimed is:
 1. A catheter comprising: a proximal shaft having afirst diameter; a distal shaft having a second diameter different fromthe first diameter; a coupling joining the proximal shaft to the distalshaft, the coupling having a hollow interior and including a distalportion and a proximal portion; and a sensor having a hollow coredisposed within a distal portion of the proximal shaft, wherein aproximal portion of the distal shaft is inserted into the hollowinterior of the coupling through a distal end of the coupling and theproximal portion of the coupling is inserted into the hollow core of thesensor and the distal portion of the proximal shaft through a distal endof the proximal shaft, and wherein the proximal portion of the couplingcomprises: a first sub-portion having an outer diameter small enough toallow insertion into the hollow core of the sensor; and a secondsub-portion having an outer diameter small enough for insertion into thedistal portion of the proximal shaft, but too large for insertion intothe hollow core of the sensor, wherein the second sub-portion ispositioned distally of the first sub-portion.
 2. The catheter accordingto claim 1, wherein an outer diameter of the coupling is smaller at thedistal end of the coupling than at a point adjacent the distal end ofthe proximal shaft.
 3. The catheter according to claim 2, wherein thedistal portion of the coupling comprises a dome shaped portion.
 4. Thecatheter according to claim 2, wherein the distal portion of thecoupling comprises a frustoconical portion.
 5. The catheter according toclaim 1, wherein a maximum outer diameter of the proximal portion of thecoupling is less than a maximum outer diameter of the distal portion ofthe coupling.
 6. The catheter according to claim 1, wherein the hollowinterior of the coupling includes an abutment surface for the proximalportion of the distal shaft.
 7. The catheter according to claim 1,wherein the coupling causes the distal shaft to be positioned coaxiallywithin the proximal shaft.
 8. The catheter according to claim 1, whereinan exterior surface of the coupling comprises a plurality of ribs. 9.The catheter according to claim 1, wherein the coupling comprises aclear polymeric material.
 10. The catheter according to claim 1, whereinthe distal shaft is formed into at least a partial loop having a fixedradius of curvature.
 11. The catheter according to claim 1, wherein thedistal shaft is formed into at least a partial loop having a variableradius of curvature.